The present invention is relative to contactless electromagnetic induced identification code ICs, especially for those ICs that designate identification code by pads"" number.
General identification codes are stored in the magnetic cards, and every card has one identification code. When a magnetic card is rushed through a card reader, the card reader could be able to identify the card user by the identification code stored in the card. But it is inconvenient for a user to take a card and rushes through the card reader for identifying. So, contactless electromagnetic induced identification code is invented to improve the usage drawback of magnetic cards.
Contactless electromagnetic induced identification code is able to identify the identification code by electromagnetic wave, which technology is shown as FIG. 1. Induction Coil 12, which locates at Card Reader 11, is able to issue magnetic power. There is a contactless electromagnetic induced identification code IC 14 and an Induction Coil 15 hided in Card 13, and an identification code is also generated in this card. When Card 13 closes to the code reader, induction coil 15 will be coupled and provides electric power for the IC because of electromagnetic induction theory, and then the code stored in the IC will pass to card reader 11 for identifying via induction coil 15 (which can be used as a magnetic induction coil). So, closing the card and the card reader but not rushing through it can identify a user""s code.
But above traditional technology is designed for security, so there is a unique identification code stored in every card""s IC. If there are 100 people that need to be identified, then it is necessary to create 100 identification codes and stored in 100 ICs respectively. Therefore we need 100 masks to implement these ICs with very high cost. This is a special requirement of non-mass production. But not suitable for mass-produced product, just likes card toils.
The mainly object of present invention is, providing a design solution for xe2x80x9ccontactlessxe2x80x9d electromagnetic induced identification code application. That is, combining IC pads with special circuit design to generate three different kinds of logical voltage exist in one pad. With this design, xe2x80x9ccontactlessxe2x80x9d electromagnetic induced identification code IC can be mass-produced and very low cost on the application of electromagnetic induced identification code.
For production cost, to generate a code in a general xe2x80x9ccontactlessxe2x80x9d electromagnetic induced identification code IC needs the total fee of an IC mask. But the solution of the present invention reduces lots of production cost, which generates several identification codes for xe2x80x9ccontactlessxe2x80x9d electromagnetic induced identification code ICs with only one mask. The theory of present invention is based on the third power (x{circumflex over ( )}3) extension of an input pad. For example, we may create 3{circumflex over ( )}3=27 kinds of identification codes by 3 input pads; by the same reason, 125 different identification codes can be created by 5 input pads; and most important of all, these different codes can be created by one mask only when the ICs are produced.
In the other words, the present invention provides a new solution for above mass-produced identification code products, which creates several identification codes in one IC chip by one mask, and reduces the production cost by special input pads and control circuit.
For above purpose, the present invention provides a kind of contactless electromagnetic identification code IC circuit, which contains a control circuit to detect an input pad, and to provide a coding signal to decide one identification code for the contactless electromagnetic induced identification code IC. The control circuit contains:
A Carry Clock signal source, which provides a carry clock signal to the input pad for generating a responding signal from the input pad; and
A flip-flop set, which connects to the input pad, decides the identification code and forms the coding signal according to the pad""s responding signal and the carry clock signal.
In accordance with one aspect of the present invention, the input pad""s responding signal contains three kinds of potential levels: a low potential level, a high potential levels, and a floating potential level.
In accordance with one aspect of the present invention, there is a buffer that locates between the carry clock signal source and the input pad.
In accordance with one aspect of the present invention, the flip-flop set is D-type.
In accordance with one aspect of the present invention, the D-type flip-flop set contains three D-type flip-flops.
In accordance with one aspect of the present invention, there is a Schmidt trigger that locates between the flip-flop set and the input pad.
In accordance with one aspect of the present invention, the coding signal is a 2-bits coding signal for presenting the three types of the input pad.
The contactless electromagnetic induced identification code IC of present invention contains one input pad at least. The input pad is used for coding purpose, which generates one of the three input pad types to decide an identification code for the contactless electromagnetic induced identification code IC.
In accordance with one aspect of the present invention, the three states of the input pad are high level, low level, and floating level.
In accordance with one aspect of the present invention, the producing process is a kind of bonding producing process.
In accordance with one aspect of the present invention, the number of input pads can be N, which is an integer that larger than 0.
In accordance with one aspect of the present invention, the N input pads decide three powers of N kinds of identification codes.
In accordance with one aspect of the present invention, the three powers of N kinds of identification codes are stored in the IC.
The present invention may best be understood through the following description with reference to the accompanying drawings, in which: